What's a good strategy for designing a room with multiple objects in it?
Room modeling tips



Transparent objects

It's often handy to make some objects such as the walls transparent for the viewport. For render they're still fully visible of course:





Furniture creation

It's good to keep the pivots of the furniture in the bottom, so that you can snap them to different surfaces with Face Snapping. You can easily rotate them around their local axis with R+ZZ (or XX or YY depending on the case):





Managing lots of objects

Sometimes it's good to make some objects non-selectable, like the walls. Layer Manager is a great addon for managing objects if you have them on different layers. 

Alternatively, parenting them to an empty is an easy way to make them non-selectable. Use Ctrl+Left click to affect all the children of a parent in Outliner:





Rendering

Sometimes it's necessary to place the camera outside of the room and mark the front walls as invisible to camera. Hiding them is not encouraged, because the light that comes outside the room makes it look dull. The light needs to bounce from the insides of your front wall:


room.blend